Week 3: Introduction to embryology

The aim of today’s lecture was to talk about what an embryo is, and give a sense of how it forms, what it looks like, and what it will become. I spoke about four principles of growth and development that are really important to the future series of embryology lectures. My underlying aim was to demonstrate why embryology is an important subject for medical students and clinicians. You don’t need to understand all the signaling processes underlying the development of the embryo, but it’s really helpful to have seen how the adult anatomy is formed and what can go wrong.
The embryonic period of development runs from fertilisation to the end of the 8th week. By this point most structures have formed and are functioning to some degree. From then to birth further development is termed the foetal period. Note that clinically the foetus is dated with reference to the last menstrual period, adding 2 weeks to the real gestation time (there’s a gap of about 2 weeks from the start of the menstrual period and ovulation).
We introduced the ideas of growth (through cellular proliferation, cellular hypertophy or accretion of matrix around cells), differentiation (stem cells become specialised), organisation (signalling molecules set up concentration gradients and cells with receptors respond according to their location), and morphogenesis (cells form more complicated structures from simple ones). Look at the lecture on Blackboard or listen to the podcasts for more on these.
We ended with a 5-question quiz about the lecture that the girls’ team won. That starts the girls off 1-0 up with a possible 9 lectures to go. I wonder what we should do for the winning team.